Serum paraoxonase‐I activity is unaffected by short‐term administration of simvastatin,bezafibrate, and their combination in type 2 diabetes mellitus

Background The high‐density lipoprotein (HDL)‐associated anti‐oxidative and anti‐inflammatory enzyme, paraoxonase‐I, has been found previously to be lower in type 2 diabetes mellitus. We studied whether statin and fibrate treatment, alone and in combination, affect serum paraoxonase‐I activity in conjunction with changes in HDL cholesterol in diabetic patients. Subjects and methods A placebo‐controlled crossover study was carried out in 14 type 2 diabetic patients to test the effect of 8 weeks of active treatment with simvastatin (40 mg daily), bezafibrate (400 mg daily), and their combination on serum paraoxonase‐I activity, measured as its activity towards arylesterase and paraoxon. Serum paraoxonase‐I activity was also compared between these diabetic patients and 49 non‐diabetic control subjects. Results Serum arylesterase activity was lower in type 2 diabetic patients compared to control subjects (P < 0·001), but the difference in paraoxonase activity was not significant (P = 0·22). Neither arylesterase (P = 0·24) nor paraoxonase activity (P = 0·37) was increased in response to treatment, despite higher HDL cholesterol and apolipoprotein A‐I during combination therapy (P < 0·05 for both). Conclusion Short‐term administration of simvastatin and bezafibrate, even when combined, is ineffective in raising serum paraoxonase‐I activity in type 2 diabetes.